This part is a replacement filter bypass cap for your refrigerator. If you intend to use an external water filtration system for your refrigerator, the bypass cap will allow you to do so. To use a filter bypass cap, simply screw it in where you would normally screw in the regular water filter. If you have a bypass system installed and your ice maker doesn’t make ice, your water dispenser doesn’t make water, or if there is water dripping inside your refrigerator, you may need to replace the bypass filter cap. This part is made of white plastic and is sold individually.